ANOTHER IMPORTANT USE OF PULSE OXIMETER IN GENERAL PRACTICE
O P Kapoor
Ex. Hon. Physician, Jaslok Hospital and Bombay Hospital, Mumbai, Ex. Hon. Prof. of Medicine, Grant Medical College and JJ Hospital, Mumbai 400 008.
HIV positive population is increasing day-by-day. By the time these patients develop the actual illness of AIDS, because of the poor immunity they start coming for illnesses like extra pulmonary tuberculosis, pulmonary tuberculosis, viral and fungal infections, etc.
One of the dangerous illnesses which they can develop, specially when the CD4 Count is less than 200, is pneumocystis carinii chest infection. The x-ray appearance of this pneumonia is often typical. There is no shadow in the apices or the bases which are spared in a patient having bilateral shadows. But the point is that this x-ray appearances appear quite late and x-ray chest could be normal.
Also the 100% diagnosis of this infection is only made if pneumocystis carinii organism is demonstrated by immuno-fluorescence studies done on the secretions collected from BAL (Broncho Alveolar Lavage).
Thus it appears that the family physician would have problems in diagnosing such a difficult and rare condition which responds dramatically to one shot of IV injection of Cotrimoxazole (even oral administration).
The following procedure may be of help to the practitioners.
If any AIDS patient develops severe cough and/or dyspnoea with or without fever and the x-ray chest is normal, pulse oximeter should be used to see his SPO2. If it is normal, tell the patient to do some exercise (ideally it should be on a treadmill). A fall in SPO2 of more than 7% will be diagnostic of pneumocystis carinii chest infection.